[x3d-public] Mantis 27.4.9 NurbSet - Change child geometry model to X3DParametricGeometryNode
John Carlson
yottzumm at gmail.com
Fri May 13 11:56:47 PDT 2022
I am not too familiar with terms like parametric (reminds me of parameters)
surface, implicit and explicit. I’m fairly sure that NURBS are parametric
equations, but not parametric surfaces. This is somewhat confusing!
Parametric geometry seems to imply interaction with geometry, like
interactively modifying a field to change the NURBS (or other) shape. This
sounds like CAD.
I have modified my surface interactively. So I would fit it under
parametric geometry, but not NURBS.
I don’t know if we should consider my surfaces for addition to the
standard. I am open to discussion. I have not tried to move my surfaces
to NURBS yet.
I believe when i was in college there was discussion of turning spheres to
NURBS, but I didn’t hear the outcome.
I think I understand the NURBS hierarchy now. I would encourage an
abstract nurbs node added to the hierarchy between the parametric geometry
and any NURBS abstracts, surfaces and curves nodes.
Then, if possible, make a “geometry set”, that NurbsSet inherits from, for
smoothing geometry.
John
On Fri, May 13, 2022 at 12:27 PM John Carlson <yottzumm at gmail.com> wrote:
> Sorry, further questions keep popping up. Are we sure that the NURBS
> Surfaces and curves directly under the X3DParametricGeometryNode can be
> smoothly aligned with the other NURBS surfaces under
> X3DNurbsSurfaceGeometryNode ? Indeed, it kind of looks like all the
> interesting stuff which may be required for smoothing may be in X3DNurbsSurfaceGeometryNode
> (compare with NurbsCurve). If we move to the higher interface, fields
> valuable to smoothing may not appear in the concrete nodes?
>
> This cones from someone with only a book knowledge of MURBS 35 or so years
> ago.
>
> Im basically wondering why there are two abstract nodes, and why X3DParametricGeometryNode
> was placed under a the Nurbs section.
>
> I have interesting parametric geometry, but i can’t ever see It smoothed
> with NURBS or placed in a NurbsSet.
>
> As a reference, imagine the surface
>
> r = radiusAverage + radiusRange * cos (numThetaLeaves * theta) * cos
> (numPhiLeaves * phi)
>
> in spherical coordinates.
>
> If X3D is extensible, where would I extend from for this surface?
>
> John
>
> On Fri, May 1 2022 at 10:13 AM Brutzman, Donald (Don) (CIbrutzman at nps.edu>
> wrote:
>
>> Looking at the ouInterface Hierarchy shows what implements those types,
>> confirming that only Nurbs nodes are involved. This also clearly
>> identifies why we shifted the interface involved.
>>
>
>>
>> +- X3DParametricGeometryNode -+- NurbsCurve
>>
>> +- NurbsSweptSurface
>>
>> +- NurbsSwungSurface
>>
>> |
>>
>> +- X3DNurbsSurfaceGeometryNode -+-
>> NurbsPatchSurface
>>
>> +-
>> NurbsTrimmedSurface
>>
>>
>>
>> Dick points out that someday in (some wonderful) future we might allow
>> other geometry nodes to get smoothly aligned next to Nurbs nodes. That
>> will be nice – but we are OK for now.
>>
>>
>>
>> all the best, Don
>>
>> --
>>
>> Don Brutzman Naval Postgraduate School, Code USW/Br
>> brutzman at nps.edu
>>
>> Watkins 270, MOVES Institute, Monterey CA 93943-5000 USA
>> +1.831.656.2149
>>
>> X3D graphics, virtual worlds, Navy robotics https://
>> faculty.nps.edu/brutzman
>>
>>
>>
>> *From:* John Carlson <yottzumm at gmail.com>
>> *Sent:* Thursday, May 12, 2022 7:39 AM
>> *To:* Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>
>> *Cc:* X3D Public Mailing List (x3d-public at web3d.org) <
>> x3d-public at web3d.org>
>> *Subject:* Re: [x3d-public] Mantis 27.4.9 NurbSet - Change child
>> geometry model to X3DParametricGeometryNode
>>
>>
>>
>> Understood, i am just trying to work through if there’s any parametric
>> geometry which isn’t NURBS, and is thus now inclusive in this modified
>> NurbsSet.
>>
>>
>>
>> Thanks!
>>
>>
>>
>> John
>>
>>
>>
>> On Thu, May 12, 2022 at 8:58 AM Brutzman, Donald (Don) (CIV) <
>> brutzman at nps.edu> wrote:
>>
>> Please be assured, no new semantics and no new functionality is being
>> proposed. We are addressing a Mantis issue that noted the NurbsSet
>> definition was unnecessarily restrictive. We adjusted the specification
>> interface to match that inclusive rationale.
>>
>>
>>
>> Changes to implementations are up to them. Since NurbsSet is a way for
>> authors to communicate when various Nurbs nodes are coincident and
>> potentially smoothable, it has no impact on functionality and might improve
>> rendering appearance by enabling smoothed seams.
>>
>>
>> Thanks for your review.
>>
>>
>>
>> all the best, Don
>>
>> --
>>
>> Don Brutzman Naval Postgraduate School, Code USW/Br
>> brutzman at nps.edu
>>
>> Watkins 270, MOVES Institute, Monterey CA 93943-5000 USA
>> +1.831.656.2149
>>
>> X3D graphics, virtual worlds, Navy robotics https://
>> faculty.nps.edu/brutzman
>>
>>
>>
>> *From:* John Carlson <yottzumm at gmail.com>
>> *Sent:* Wednesday, May 11, 2022 10:40 PM
>> *To:* Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>
>> *Cc:* X3D Public Mailing List (x3d-public at web3d.org) <
>> x3d-public at web3d.org>
>> *Subject:* Re: [x3d-public] Mantis 27.4.9 NurbSet - Change child
>> geometry model to X3DParametricGeometryNode
>>
>>
>>
>>
>>
>> Don, I'm a bit unsure of the new semantics for NurbsSet....it includes
>> other parametric geometry nodes which aren't NURBS?
>>
>>
>>
>> Would ParametricGeometrySet be a better name than NurbsSet, or a good
>> addition to X3D4?
>>
>>
>>
>> Is it counterintuitive to look for a "ParametricGeometrySet" inside NURBS
>> sections?
>>
>>
>>
>> How does this impact browser implementations?
>>
>>
>>
>> I don't know if the standard includes parametric, implicit, etc.
>> descriptions?
>>
>>
>>
>> Are we planning on dropping X3DNurbsSurfaceGeometryNode in the future?
>>
>>
>>
>> NURBS seems a bit specialized, but at least I know I'm looking for
>> NURBS. Parametric seems *way* general, and should probably remain at the
>> abstract level.
>>
>>
>>
>> I have no other issues that come to mind presently.
>>
>>
>>
>> I'm a bit leery of Mantis, so I will now review your next email. My
>> summary: Can one include more than one abstract type in the allowable
>> types? That is, allow both X3DParametricGeometryNode
>>
>> and X3DNurbsSurfaceGeometryNode sub node types for geometry?
>>
>>
>>
>> Thanks!
>>
>>
>>
>> John
>>
>>
>>
>> On Wed, May 11, 2022 at 8:06 PM Brutzman, Donald (Don) (CIV) <
>> brutzman at nps.edu> wrote:
>>
>> NurbsSet should be inclusive about which nodes an author thinks can be
>> rendered together as one smooth surface.
>>
>>
>>
>> - Mantis 27.4.9 NurbSet - Change child geometry model to
>> X3DParametricGeometryNode
>> - https://www.web3d.org/member-only/mantis/view.php?id=700
>>
>>
>>
>> - X3D4 Architecture, NURBS component, 27.4.8 NurbsSet
>> -
>> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/nurbs.html#NurbsSet
>>
>>
>>
>> Since X3DParametricGeometryNode includes X3DNurbsSurfaceGeometryNode,
>> changed all three NurbsSet geometry fields from X3DNurbsSurfaceGeometryNode
>> to X3DParametricGeometryNode.
>>
>>
>>
>> NurbsSet : X3DChildNode, X3DBoundedObject {
>>
>> MFNode [in] addGeometry [X3DParametricGeometryNode]
>>
>> MFNode [in] removeGeometry [X3DParametricGeometryNode]
>>
>> MFNode [in,out] geometry [] [X3DParametricGeometryNode]
>>
>> SFNode [in,out] metadata NULL [X3DMetadataObject]
>>
>> SFFloat [in,out] tessellationScale 1.0 (0,∞)
>>
>> SFVec3f [] bboxCenter 0 0 0 (-∞,∞)
>>
>> SFVec3f [] bboxSize -1 -1 -1 [0,∞) or −1 −1 −1
>>
>> }
>>
>>
>>
>> This changes X3DUOM and possibly some implementations. Comments welcome.
>>
>>
>>
>> We current intend to accept this change as resolved once X3DUOM is
>> updated.
>>
>>
>>
>> all the best, Don
>>
>> --
>>
>> Don Brutzman Naval Postgraduate School, Code USW/Br
>> brutzman at nps.edu
>>
>> Watkins 270, MOVES Institute, Monterey CA 93943-5000 USA
>> +1.831.656.2149
>>
>> X3D graphics, virtual worlds, Navy robotics https://
>> faculty.nps.edu/brutzman
>>
>>
>>
>> _______________________________________________
>> x3d-public mailing list
>> x3d-public at web3d.org
>> http://web3d.org/mailman/listinfo/x3d-public_web3d.org
>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://web3d.org/pipermail/x3d-public_web3d.org/attachments/20220513/984209e8/attachment-0001.html>
More information about the x3d-public
mailing list